From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-yw1-f202.google.com (mail-yw1-f202.google.com [209.85.128.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 053AF14659C for ; Tue, 24 Sep 2024 21:20:35 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727212839; cv=none; b=OxTQhjhQVuKPp9//RTM6Wa6A/UNyoJvnxIho0591sFGONvkFxNzxJ3KVUhkSffAY8qawlg3zhacWlVVYAL5bHeCiG19lOa2/Mx5B8RE7lPDgmPaejj9vifIQq0rg0SNNfM9tgFyI/EWbQbrj/II/XEQ5X9oBGXP4sBq60pXopcc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1727212839; c=relaxed/simple; bh=Mm95RZ0gEd/5ILA/sw+Yul4T3HW7v3bJsG9qmFVzqME=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=E+Q/yI5oWE6FtE9WqBX+Ah6Sq3Pxkx86lHazjZN2wfA5b3QJk/1tHNoSZj2r+zrbkokY7rgvtxYUrUXr2fbzM1liGwXkd5dKGHgcztWwjBTbZDlIUSY99Ni0YGnxDxTTOB490hWw2aODPQe1cyfq/NHKk633x/GOHFyoGL7qYDI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--mmaurer.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=TAsgADau; arc=none smtp.client-ip=209.85.128.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--mmaurer.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="TAsgADau" Received: by mail-yw1-f202.google.com with SMTP id 00721157ae682-6db7a8c6831so97566797b3.3 for ; Tue, 24 Sep 2024 14:20:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1727212835; x=1727817635; darn=lists.linux.dev; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=+9YZzoCvxvyDdM8B+em9dMKSDuRRuGPZhSev+lAnN9E=; b=TAsgADau6dHtYXzmZWQfRtW52OIgJDzsSkMBvEdK47XuBt4Kw30GvTX86K5MKmBL87 c2obE2G2iqTvD7lpeMEdXsQhu+mOW+bO1aiyQkHi3vVEIIwPcLHitQOeFc1M+3sryu2A VsX9m+6CNlUyPt48LWROE/il2yl5clt+eFiSbk1qR7Ex8VawEuWt+iuR9O6kn4ELBFxh KapGNeYo7dGuTQ+GJFh/xLnHJrqUfqka1FAbUQNmgqhVin1SGSfpb2LZg0aU12pzkIfi pvW9hujvVh14LF5r+Fu0vR7JTsq3Os8w518yQr5lTRLeLJHolZoA6QyQnR9IChDDohGB W4rQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1727212835; x=1727817635; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=+9YZzoCvxvyDdM8B+em9dMKSDuRRuGPZhSev+lAnN9E=; b=UJO++mmA8KeYefO73NH+dFJ9V2oEALlz+rIuDetGfMCpgKtaoTwlCAyba94o/qDP+0 XPvTGrSe4C+Tl6+zgjkVZAhJvkxsV2QlWNutdkTS6XKSNeOmGKRhdacYnm9fOStSP+5C kDSMOzaX5LpDlegnoohSZhmwxC6AWBUWpo4iWPlP7V1m8k0oUMVf7FesXpMGX+2rIMyo xsjp9j3mE4f8Kfow+X1IR1fKTUOwcN7Z6LwWAaRGlN0eAGg/blBGBtH9LuR+TxrzzzKO 5r+3ByKfsHUYsKO6cy0LLogoEoCBGQUHn0si+QGthxrPNBO9IK3CFRx63rowthMaNkxp hTsA== X-Forwarded-Encrypted: i=1; AJvYcCX193CyIu/eA1asRWIxibQObCsRH7OcUZ4BGLTFQcy2v2JiSgK0cS4aYFKhrpzqeW34uw/SZw==@lists.linux.dev X-Gm-Message-State: AOJu0YwzvIAvmZT03Nqum4+2PdhYsxOD711c4HxficCoMdIGe6MHHSdr 00iaruiOIj5reyliPCOAPZsdgURIMyU92JTLsmCHi7+W2QxFSuQNvX3EIOwe8UZrRR8wFKS+30p EIHmu+A== X-Google-Smtp-Source: AGHT+IH8GJCD2yEItqoVxha2hna+M6u5pXhuHD6Vku3ryEFGXz3pSAiDfCy7EoF1TJPoKA1RIGRpct8983ar X-Received: from anyblade.c.googlers.com ([fda3:e722:ac3:cc00:20:ed76:c0a8:1791]) (user=mmaurer job=sendgmr) by 2002:a05:690c:5092:b0:6dd:bcce:7cd4 with SMTP id 00721157ae682-6e21d81e792mr11447b3.2.1727212834850; Tue, 24 Sep 2024 14:20:34 -0700 (PDT) Date: Tue, 24 Sep 2024 21:19:44 +0000 In-Reply-To: <20240924212024.540574-1-mmaurer@google.com> Precedence: bulk X-Mailing-List: asahi@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20240924212024.540574-1-mmaurer@google.com> X-Mailer: git-send-email 2.46.1.824.gd892dcdcdd-goog Message-ID: <20240924212024.540574-3-mmaurer@google.com> Subject: [PATCH v4 02/16] module: Factor out elf_validity_ehdr From: Matthew Maurer To: masahiroy@kernel.org, ndesaulniers@google.com, ojeda@kernel.org, gary@garyguo.net, mcgrof@kernel.org, Alex Gaynor Cc: rust-for-linux@vger.kernel.org, linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org, neal@gompa.dev, marcan@marcan.st, j@jannau.net, asahi@lists.linux.dev, Matthew Maurer , Petr Pavlu , Sami Tolvanen , Daniel Gomez , Boqun Feng , "=?UTF-8?q?Bj=C3=B6rn=20Roy=20Baron?=" , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , linux-modules@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Factor out verification of the ELF header and document what is checked. Signed-off-by: Matthew Maurer --- kernel/module/main.c | 70 +++++++++++++++++++++++++++++--------------- 1 file changed, 47 insertions(+), 23 deletions(-) diff --git a/kernel/module/main.c b/kernel/module/main.c index 1a2dd52147ba..59c977acfb44 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -1664,6 +1664,50 @@ static int validate_section_offset(const struct load_info *info, Elf_Shdr *shdr) return 0; } +/** + * elf_validity_ehdr() - Checks an ELF header for module validity + * @info: Load info containing the ELF header to check + * + * Checks whether an ELF header could belong to a valid module. Checks: + * + * * ELF header is within the data the user provided + * * ELF magic is present + * * It is relocatable (not final linked, not core file, etc.) + * * The header's machine type matches what the architecture expects. + * * Optional arch-specific hook for other properties + * - module_elf_check_arch() is currently only used by PPC to check + * ELF ABI version, but may be used by others in the future. + * + * Return: %0 if valid, %-ENOEXEC on failure. + */ +static int elf_validity_ehdr(const struct load_info *info) +{ + if (info->len < sizeof(*(info->hdr))) { + pr_err("Invalid ELF header len %lu\n", info->len); + return -ENOEXEC; + } + if (memcmp(info->hdr->e_ident, ELFMAG, SELFMAG) != 0) { + pr_err("Invalid ELF header magic: != %s\n", ELFMAG); + return -ENOEXEC; + } + if (info->hdr->e_type != ET_REL) { + pr_err("Invalid ELF header type: %u != %u\n", + info->hdr->e_type, ET_REL); + return -ENOEXEC; + } + if (!elf_check_arch(info->hdr)) { + pr_err("Invalid architecture in ELF header: %u\n", + info->hdr->e_machine); + return -ENOEXEC; + } + if (!module_elf_check_arch(info->hdr)) { + pr_err("Invalid module architecture in ELF header: %u\n", + info->hdr->e_machine); + return -ENOEXEC; + } + return 0; +} + /* * Check userspace passed ELF module against our expectations, and cache * useful variables for further processing as we go. @@ -1693,30 +1737,10 @@ static int elf_validity_cache_copy(struct load_info *info, int flags) unsigned int num_info_secs = 0, info_idx; unsigned int num_sym_secs = 0, sym_idx; - if (info->len < sizeof(*(info->hdr))) { - pr_err("Invalid ELF header len %lu\n", info->len); - goto no_exec; - } + err = elf_validity_ehdr(info); + if (err < 0) + return err; - if (memcmp(info->hdr->e_ident, ELFMAG, SELFMAG) != 0) { - pr_err("Invalid ELF header magic: != %s\n", ELFMAG); - goto no_exec; - } - if (info->hdr->e_type != ET_REL) { - pr_err("Invalid ELF header type: %u != %u\n", - info->hdr->e_type, ET_REL); - goto no_exec; - } - if (!elf_check_arch(info->hdr)) { - pr_err("Invalid architecture in ELF header: %u\n", - info->hdr->e_machine); - goto no_exec; - } - if (!module_elf_check_arch(info->hdr)) { - pr_err("Invalid module architecture in ELF header: %u\n", - info->hdr->e_machine); - goto no_exec; - } if (info->hdr->e_shentsize != sizeof(Elf_Shdr)) { pr_err("Invalid ELF section header size\n"); goto no_exec; -- 2.46.1.824.gd892dcdcdd-goog